1. Field of the Invention
The present invention is directed to an x-ray video system, and a method for operating such a system, for the transillumination of an examination subject wherein a video image corresponding to an x-ray image of a patient is generated on a display device, and wherein the x-ray beam used to generate the transillumination image is gated by a primary radiation diaphragm having a plurality of moveable diaphragm plates.
2. Description of the Prior Art
An x-ray video system is described in the periodical "Roentgenpraxis," 6/1981, pages 234-246 wherein an x-ray tube is used to generate an x-ray beam which is limited by a primary radiation diaphragm having a plurality of adjustable diaphragm plates. The x-ray beam is incident on a patient, and the resulting x-ray image is supplied via an x-ray image intensifier to a video chain with a video display. An image memory and image processing means are provided between the video camera, which is connected to the image intensifier, and the display. In this known system, if only a particular organ or region of a patient is of interest, the diaphragm plates of the primary radiation diaphragm are adjusted so that the x-ray beam is gated to transirradiate only the area of interest. The diaphragm plates generate shadows on the transillumination image, which are visible on the display, and are used to bring the diaphragm plates to the required position. This procedure can take a considerable time under certain circumstances, so that the patient may risk exposure to a radiation dose which is not negligible in comparison to the radiation dose required for the actual examination.